Freight elevator door latch



y 1960 J. M. JECMEN, JR 2,936,046

FREIGHT ELEVATOR DOOR LATCH Filed Oct. 24. 1957 nited States Patent F FREIGHT ELEVATOR DOOR LATCH James M. Jecmen, Jr., Brook'field, Ill.

Application October 24, 1957, Serial No. 692,125 2 Claims. (Cl. 187 59) This invention relates to latches for use in connection with freight elevator doors of either the motor or manually operated type. Such doors are composed of a pair of counterbalanced vertically movable sections movable simultaneously in opposite directions in a vertical plane.

The purpose of my present invention is to prevent the accidental or unintentional opening of such doors. Latches for this purpose which are required to be manually operated or released are in common use. My present invention, however, aims to eliminate the necessity of manual operation of the latch and provides a latching mechanism which acts automatically to latch the door sections in closed position and is adapted to be automatically released upon the application of a predetermined force applied to open the doors.

A further object is to provide a latch which will be extremely simple in construction and operation so that it can be economically manufactured and installed and which will not be likely to get out of order. Furthermore, the construction of the latch is such that it is devoid of springs or other delicate parts which might become readily broken or damaged.

Another object of my invention is to provide a latch which will be efiective to hold the door sections in closed position, irrespective of whether the interposed astragal is of full size or is partially collapsed or entirely missing, so as to permit the door sections to approach each other to varying degrees.

Additional objects and advantages of my invention should be apparent to those skilled in the art from the following description when considered in connection with the accompanying drawing illustrating a preferred embodiment thereof.

On the drawing,

Figure 1 is an elevation of a counterbalanced elevator door equipped with a latch embodying my invention;

Fig. 2 is an enlarged fragmentary view of the lefthand latch shown in Fig. 1; and

Fig. 3 is a fragmentary elevation looking toward the right at the structure disclosed in Fig. 2.

Referring to the drawing more in detail,the upper and lower sections of a conventional freight elevator door are designated by reference characters 5 and 6, respectively. These sections are operatively connected by a chain 7 at each side of the door, each chain being trained over a sheave 8 fixedly mounted in proximity to the upper door section, one end of the chain being connected with the lower door section through the medium of a laterally projecting boss or bracket 9 and the other end of the chain being connected with the upper section 5 through the intermediary of the latch member in a manner which will be later described more in detail.

In installations embodying my invention, a latch is employed at each side of the door, as illustrated in Fig. 1 of the drawing. Since the latches, however, are duplicates in construction and operation, except that one is a righthand and the other is a lefthand latch, a detailed description of one only will suffice for an understanding 'ice of my invention. I have, therefore, illustrated on Figs. 2 and 3 of the drawing only the latch illustrated at the left in Fig. 1.

Upon a spindle or bolt 11 carried by the frame of the lower door section 6 there is rotatably mounted a cam follower 12 in the form of a roller rotatably disposed upon the spindle 11. A retainer disc 13 serves as a keeper and guide for the latch member which will be later described.

A bracket 14 carried by the upper door section 5 serves as a support for a pintle or pivot pin 15 upon which is pivotally mounted a latch member consisting of a cam shaped portion 16 and an arm portion 17. Both portions are pivotally mounted uponthe pivot pin 15 and are adjustably connected together by a bolt 18 positioned in the desired one of a plurality of holes 19 in the portion 17. A single hole for the bolt 18 in the cam shaped portion of the latch enables adjustment of the relative positions of the portions 16 and 17 by locating the connecting bolt 18 in the selected hole 19.

From Figs. 2 and 3 it will be apparent that the connection between the chain 7 and the door section is established through the latch member above described. Since the chain is attached to the upper end of the arm portion 17 of the latch member, upward tension exerted by the chain 7 positions the latch member 17 upon its pivot in position to cooperate with the roller .12 in restraining the door sections against opening movement.

A portion 16 of the latch member is shaped to pro vide the cam surface 21 extending obliquely to the vertical and the cam surface 21 also disposed obliquely to the vertical but at an angle to the surface 20 so that said cam surfaces intersect at the hump 22 of the cam.

The cam surfaces 20 and 21 are disposed in the path of travel of the cam roller 12., so that as the door sections approach closing position the roller 12 will engage and ride up the surface 21, thereby swinging the lower end of the latch member to the left viewing Fig. 2 until the roller reaches the hump 22, as illustrated in dotted lines designated 23 in Fig. 2. Beyond the hump the roller will travel along the cam surface 211 until the door sections are in fully closed position. The position of the roller 12 on the cam surface 20 at such time will depend upon the degree of separation between the upper and lower sections. This degree is determined by the one or more astragals 24 interposed between the door sections. If these astragals become partially collapsed, the roller will travel a correspondingly greater distance up the cam surface 20 and, should they become entirely displaced, the roller would travel to the upper limit of the cam surface 20, thereby permitting the latch member to assume the dotted line position indicated by reference character 25 in Fig. 2..

It will be apparent, therefore, that irrespective of the spacing between the opposed edges of the upper and lower door sections which is determined by the resistance of the astragal, the latch member under the tension exerted by the connecting chain 7 will be urged into engagement with the cam follower 12 throughout a variable range of separation of the door sections to yieldably hold the door in closed position or at least restrain the accidental or unintentional opening of the door. "The door can, however, be opened without the necessity of either automatically or manually releasing a positive lock, by the mere application of a substantial downward pressure applied to a foot pedal 26 disposed near-the bottom of the lower door section. The engagement of the inclined cam surface 20 of the latch member with the follower 12 not only offers substantial resistance to separation of the door sections, but also by reason of the inclination of the cam surface tends to urge the door sections toward each other as far as the astragal permits.

While I have shown and described that embodiment of my invention which at present seems preferable, it should be understood that variations in the structural details and in the proportions of parts illustrated may be resorted to within the scope of my invention as defined in the following claims.

I claim:

1. A latch for sectional elevator doors, comprising counterbalanced vertically movable upper and lower sections, a roller mounted on the lower door section, a latch member pivotally mounted on the upper door section, said latch member being composed of a lower cam arm having a locking cam surface which cooperates with said roller and an upper arm, said locking cam surface having a straight-line cam face disposed obliquely to and in'the path of travel of said cooperating roller, a chain attached to said upper latch arm, a guide frame having a pulley with said chain running over said pulley and connecting to said lower door section, the arms of the latch member being adjustably connected through a series of positions which will vary the chain tension on the latch whereby said latch member is biased to urge said cam surface against the cooperating roller and thereby yieldably resist separation of said door sections throughout a variable range of closed positions of said door sections.

2. A latch for sectional elevator doors, comprising counterbalanced vertically movable upper and lower sections, a cam follower mounted on the lower door section, a latch member pivotally mounted on the upper door section, said latch member having an upper portion, a lower cam arm having a locking cam surface and means for adjustably connecting said upper portion and lower cam arm, said locking cam surface having a straight-line cam face disposed obliquely to and in the path of travel of said cam follower, and meansattached to said upper portion and connected to the lower door section for operatively connecting said door sections, said locking cam surface being yieldablyv urged into engagement against said cam follower and thereby yieldably resisting separation of said door sections throughout a variable range of closed positions.

References Cited in the file of this patent UNITED STATES PATENTS 531,116 Hamshaw Dec. 18, 1894 676,474 Saino June 18, 1901 1,060,484 Newton Apr. 29, 1913 2,592,239 Brown Apr. 8, 1952 2,659,457 Doeg Nov. 17, 1953 

